Keynote Video Thumbnail/Poster Frame

Okay, this has been a problem for super-users of Keynote forever and I honestly can't believe Apple has not solved this problem after all these years.

I use Keynote for an awards ceremony every year. It's always customized with transitions that cannot be recreated or emulated with the standard Keynote transitions - they are built in After Effects. It otherwise works seamlessly, looks amazing and is 100% click through so it can match the timing of the presenters. The problem is that the presentation is about 90% movie files where the first frame of the next video looks identical to the last frame of the video you're currently on so the "Next Slide" preview is confusing to the tech staff manning the presentation - they have to work on faith (supplemented by presenter notes assuring them the next slide gets to the right point eventually). And, of course, there's the age old problem that if you select a poster frame for the movie file, it will flash that frame when you advance to the next slide which ruins the whole custom transition effect.

[Edited by Moderator]